Card Star is an application that keeps track of your loyalty cards.
I was one of the thousands of people that helped propel this application into the top slots in the iTunes store. It was featured in an Apple ad and I grabbed it.
The point is that you never have to remember your loyalty cards, enter the data and when you go to a store, recall it, and the merchant can scan you iPhone screen. Neat idea. I don’t have enough loyalty cards that I care to go through the hassle of entering them.